The estimated time of arrival or ETA is a measure of when an aircraft is expected to arrive at a certain place. For aircraft, there may be various ETAs that are used by both the airline and the traveling public. For example, one ETA may be a prediction of when the aircraft will land on a runway. This estimated landing time is sometimes referred to as the estimated ON time. Another ETA may be when the aircraft will reach the gate at which it is to discharge or board its passengers. This estimated gate arrival time is sometimes referred to as the estimated IN time. This ETA information is used by the airline to inform its passengers and other persons (e.g., the persons picking up the passengers) so that people do not waste time waiting for an aircraft by planning when to arrive at the airport. In addition, the airline may also use this information for a variety of other reasons, e.g., to schedule gate employees, to ensure that a gate is available for an incoming flight, etc.